The effects of differential irrigation treatments on the water use of broccoli (c.v. Indurance) and carrots (c.v. Stefano) were studied in the rainy, winter season from July to September 2006 and in the dry, summer period from November 2006 to March 2007, respectively. Broccoli and carrots are produced on the Swan Coastal Plain region on Grey Phase Karrakatta Sand. Such soils generally have water holding capacities as low as 10 to 13%. This soil is typical to the Swan Coastal Plain and requires irrigation to be applied at rates of up to 150% of class A pan evaporation (Epan) to optimise growth and quality. / High spatial uniformity (an average of 90%) of water distribution (DU) was achieved with the sprinkler irrigation system. The average irrigation water use efficiencies (Eu) in both the experiments were relatively high, at 78% and 95% in broccoli and carrot trials, respectively. The numerous rainy days during the winter season affected the results of water application efficiencies (Ea) of the broccoli experiment, which ranged from 35% to 43%. This contrasted with the carrot experiment where the water application efficiencies (Ea) of the 100% Epan and Crop Factor (CF) treatments were 81% and 78%, respectively. For the carrot experiment the water application efficiencies for the 100% Epan and crop factor treatments were 14% higher than the 150% Epan treatment. These results indicate that the sprinkler irrigation systems in both experiments showed good performance makes the system suitable for experimental purposes and also for vegetable production on soils of this nature. / Despite the differences in irrigation volume, soil water contents remained very high and did not differ among treatments in both the experiments. The differential soil water stress index (DSWSI) for the 100% Epan (T1) and variable water replacement (VR) (TVR) treatments ranged from 0.74 to 1.71 for both broccoli and carrot trials. There were only small soil water tension differences among all the irrigation treatments and ranged from -2.4 kPa to -7.6 kPa, which was within the range between saturation and field capacity for sandy soil (0 to -10 kPa). / In the broccoli experiment, even though the 150% Epan (T2) irrigation treatment received 46% and 61% more irrigation than the 100% Epan (T1) and variable water replacement (TVR) irrigation treatments respectively, the treatments appeared to be largely negated by the high incidence of rainfall during the growing season. For example, the total depth of water application at 150% Epan was 13.9% and 17.2% greater than 100% Epan and TVR treatments respectively. As such the yield, biomass components and nutritional value (ascorbic acid and carotenoid content) did not vary among the treatments. However, irrigation was still required based on the set scheduling parameters and when considered in isolation of rainfall the irrigation crop water use efficiency (WUEi) on T1 and TVR treatments increased by 1.6-fold compared to T2 treatment. / For the carrot experiment the total depth of water application (rainfall and irrigation) for the 150% Epan treatment was 33% and 23% greater than at 100% Epan and Crop factor (CF) treatments, respectively. The yield (carrot roots) on a fresh weight basis (FW) for plants irrigated with the 150% of Epan and Crop factor (CF) treatments were 16% and 20% higher than the yield for plants irrigated with the 100% Epan treatment. Total (root and shoot) fresh weight of carrot plants irrigated For the carrot experiment the total depth of water application (rainfall and irrigation) for the 150% Epan treatment was 33% and 23% greater than at 100% Epan and Crop factor (CF) treatments, respectively. The yield (carrot roots) on a fresh weight basis (FW) for plants irrigated with the 150% of Epan and Crop factor (CF) treatments were 16% and 20% higher than the yield for plants irrigated with the 100% Epan treatment. Total (root and shoot) fresh weight of carrot plants irrigated with the CF treatment was 17% higher than the total fresh weight of plants irrigated with the 100% Epan treatment. However, there were no significant differences between irrigation treatments for root and total (root and shoot) mass on a dry weight basis and the ratio of carrot root to shoot, on a fresh and dry weight basis. The root lengths for plants grown with the CF and 150% Epan irrigation treatments averaged 30 cm, and were 14% larger than the root lengths for the 100% Epan treatment. The plant height for plants grown with the CF irrigation treatment was 6% higher than at the 100% Epan irrigation treatment and leaf length at the CF irrigation treatment was 12% greater than at the 150% Epan irrigation treatment. The root diameter and leaf width of carrots were not significantly different for all treatments. There were no significant differences in ascorbic acid and total carotenoid content of carrot roots among the three irrigation treatments. The average values of antioxidant content from diphenylpicrylhydrazyl (DPPH) scavenging, ARP (anti radical power) and total trolox equivalent antioxidant capacity were 44.83%, 0.8789 and 1.056μmol TE/g, respectively. The reduction of the irrigation level treatment from the 150% Epan water replacement to the 100% Epan water replacement increased the percentage of the DPPH scavenging by 1.55%, and total antioxidant capacity (AOC) and ARP activities by 4.19%. / On a dry weight basis, the crop water use efficiencies (WUE) (irrigation plus rain water) of carrot plants irrigated with the 100% Epan and CF treatments, were the same (0.013 g/mm). However, these were 30% greater than the WUE values of carrots irrigated with the 150% Epan treatment. On a fresh weight basis, the WUE of carrot plants irrigated with the 100% Epan and CF (0.120 and 0.132 g/mm) treatments were 14% and 26% greater than the WUE of carrot plants irrigated with the 150% Epan treatment, respectively. / An example of the diurnal trends of the carrot’s physiological responses to the irrigation treatments showed that on average, the rate of photosynthesis, stomatal conductance and intercellular CO2 for carrot plants grown with the 150% Epan treatment was higher than the rate of photosynthesis, stomatal conductance and intercellular CO2 at both the 100% Epan and CF treatments. However, not all the physiology measurements showed a significant difference among all the treatments. The variation in the physiological measurements was predominantly influenced by the change of temperature during the diurnal hours. / This study has proven the hypothesis that, on a free draining sandy soil, the irrigation treatments did not affect the growth and yield. However, there was a potential to reduce irrigation volumes from standard industry levels to maximise the WUE without decreasing the yield and crop quality, especially for broccoli and carrot, in Western Australia.

Mass, solute (chloride), isotope (deuterium) and thermal balances were completed at Perry Lakes, two semi-permanent 'water table' lakes near Perth, Western Australia. All balance components except groundwater discharge/recharge were measured independently. These difficult to measure groundwater components of lake-aquifer interaction were estimated by integrating mass, solute and chloride data in sequential 4 day balances spanning two years. Before urbanisation, such wetlands functioned predominantly as flow-through lakes. Now, large winter storm water inputs (and summer artificial level maintenance pumped locally from groundwater) dominate. In East Lake these inputs together comprise 42% of the annual water budget; groundwater discharge is reduced to just 2%. Even under flow-through conditions, these 'non natural' inputs are so large East Lake always tends towards a recharge state and commonly becomes a local groundwater mound. Flow-through is established in both lakes over winter. Initially each lake functions separately however as winter progresses shared capture and release zones are established. Maintenance of lake levels in early summer forces East Lake back to recharge status. Sediment heat flux (Qse) is significant in these very shallow lakes. Over summer Qse was negative, with a net movement of heat from the water into the sediments which act as a seasonal heat sink. In winter Qse was positive and stored summer heat was returned to the water column. This flux at times exceeded 40 W m-2. Evaporation was determined independently by floating pan, leaving Qse as the thermal balance residual. Ignoring Qse, annual evaporation determined by thermal balance was over estimated by 7%. Over and under estimates of individual 12 day balance period evaporation exceeded 50%. Monthly Class A (Perth airport) pan coefficients varied from 0.54 (January) to 0.86 (September). Ten empirical equations for evaporation were calibrated and compared with the East Lake floating pan. Best performer was the Makkink which tracked the floating pan closely throughout all seasons. Poorest were the Penman, DeBruin-Keijman, Priestly-Taylor and Brutsaert-Stricker which grossly over estimated late winter evaporation. Transpiration from Typha orientalis, estimated using hydrograph techniques was 43% of open water evaporation in summer and 28% annually. Temperature controlled evaporation pans (tracking lake temperature) experimentally determined the local deuterium content of lake evaporate ƒÔE, required for isotopic balances. Techniques employing pans evaporated to dryness and pans evaporated at constant volume were run in tandem continuously for two years. This study singularly integrates mass, solute and isotope balances thereby allowing groundwater components to be accurately quantified. The isotope balances are unique, being the only such balances incorporating experimentally derived local deuterium values of lake evaporate. This study represents the only thermal balance, the only accurate determination of pan-lake coefficients and the first calibration of commonly used empirical evaporation equations for Swan Coastal Plain wetlands. Groundwater levels in the western suburbs of Perth have declined over 40 years and a disproportionate larger decline now seriously threatens Perry Lakes. Modelling suggests regional groundwater extraction exceeds recharge. Wetland managers can no longer maintain East Lake via local groundwater extraction. Artificial recharge using imported surface and waste water are possible future management options.

Relatively little published information on cyanoprokaryote (blue-green algal) blooms in the freshwater wetlands in Western Australia is available. There has been little research on the urban lakes and rivers, examining the relationship between environmental conditions and toxin-producing blooms. In this project the ecology, morphology and toxicity of cyanoprokaryota blooms in 27 metropolitan lakes and sumplands, as well as three major rivers, from 2000 to 2003, on the Swan Coastal Plain (SCP) in the southwest of Western Australia were investigated. / A total of 24 species were identified and described, of which nine species had not been previously documented in the area. This included the potentially toxic species Cylindrospermopsis raciborskii, Aphanizomenon ovalisporum and Anabaena bergii var. limnetica. An illustrated guide to the common bloom-forming species was generated using conventional taxonomic criteria. / Microcystis flos-aquae and Microcystis aeruginosa were the dominant bloom-forming cyanoprokaryotes, widespread in their distribution. Anabaena circinalis, A. bergii var. limnetica and Anabaenopsis elenkinii were the common filamentous species. Anabaena circinalis was common to certain freshwater sites, while A. bergii var. limnetica and A. elenkinii occurred in salinity ranging from fresh (< 1ppt) to hyposaline (3-10 ppt). Sites with similar species assemblages were identified using two-way indicator species analysis and clustering analysis. From this, a distinct distribution pattern emerged, which was defined by the main genera observed in the lakes – Microcystis, Anabaena, Aphanizomenon and Anabaenopsis. / The spatial and temporal distribution of the common bloom-forming cyanoprokaryote species was examined in conjunction with spring-summer physico-chemical data using principal component analysis. It was found that pH, water temperature and electrical conductivity/salinity accounted for variations among the lakes, with electrical conductivity the variable explaining the greatest variation. Lakes located on the coast, or further inland at the base of the Darling Scarp, were more hyposaline to saline, and the remaining lakes were fresh. Although the SCP lakes form consanguineous groups based on geochemistry and hydrology, no similarities among them were found in terms of water quality. / The relationship between nitrogen (N) and phosphorus (P) concentrations (total and dissolved inorganic) and cyanoprokaryote community structure (N-fixing versus non-N-fixing species) was investigated in five selected lakes; Yangebup Lake, Bibra Lake, Blue Gum Lake, Tomato Lake and Emu Lake. The lakes ranged from mesotrophic to eutrophic and supported spring-summer blooms containing multiple species. Overall an inverse relationship between cyanoprokaryote abundance and total ambient nutrient concentrations at the time of the blooms was evident. No transition in dominance in the community was observed in Yangebup Lake, Emu Lake and Bibra Lake, as they were dominated by non-heterocytic species (M. aeruginosa and M. flos-aquae) throughout spring and summer. For Yangebup Lake and Bibra Lake, the abundance of non-heterocytic species decreased concomitantly with decreasing dissolved inorganic N. In contrast, heterocytic species (A. circinalis) dominated the spring community in Tomato Lake, and summer community in Blue Gum Lake, when N and P concentrations were at their highest. / The presence of microcystins in Microcystis dominated blooms was examined using high performance chromatography. A total of 32 natural bloom samples, representing 13 lakes, were analysed for microcystin variants; -LR, -RR and -YR. Twenty-eight samples proved to be toxic with the highest total microcystin concentration from 1645 to 8428.6 µg L[superscript]-1, the lowest concentrations were less than 10 µg L[superscript]-1 with some below the detection limit. Microcystis aeruginosa and M. flos-aquae were associated with these microcystin-containing blooms, although M. flos-aquae appear to be less toxic. The presence of Nodularia spumigena in the Lake Yangebup was associated with high concentrations of nodularin (1664 µg L[superscript]-1). / Employing enzyme-linked immunosorbent assay for microcystins and the brine shrimp (Artemia) bioassays allowed a greater number of lake samples to be analysed and provided a rapid assessment of toxicity. The three methods for cyanotoxin detection verified Yangebup Lake, Herdsman Lake, Hyde Park, Jackadder Lake and Emu Lake as highly toxic sites. Low toxicity was demonstrated in samples from Lake Goollelal, Lake Joondalup, Lake Claremont, Blue Gum Lake and North Lake. These results provided the first evidence of cyanotoxin producing blooms in urban lakes of the SCP. / A comparative study on cyanoprokaryota blooms in Swan River estuary, upper Canning River and upper Serpentine River found that these sites, although hyposaline to saline, contained species that were common in the freshwater lakes. Sampling the river systems showed M. aeruginosa, M. flos-aquae, A. circinalis, A. elenkinii and Planktothrix planctonica to be cosmopolitan in distribution, present in SCP wetlands of varied salinity. Similarities between the upper Canning River and lakes in environmental conditions and species assemblage were demonstrated using multivariate analyses. / Toxin analysis of bloom samples from the Swan River and upper Canning River revealed microcystin concentrations were less than that of the surrounding lakes (1.05-124.16 µg L[superscript]-1). Similarly, nodularin concentrations were higher in Yangebup Lake than the upper Serpentine River. However, the dominance of Anabaena in Canning River samples, and the highly toxic result from the Artemia bioassay suggests microcystin is not the predominant cyanotoxin in this wetland. / This study has produced an overview of the distribution and morphology of cyanotoxin-producing cyanoprokaryotes in the SCP wetlands. The data presented provide the basis for further cyanoprokaryote research in Western Australia, in particular the molecular characterisation of bloom-forming toxic species.